Gas turbine engines may include multiple gas flows at different temperatures and pressures. For example, the engine may have a primary or core air flow and a separate cooling air flow. In some locations, seals may be used to prevent or limit the gas flow from one area of the engine to another and/or to maintain separation of the different gas flows.
Gas turbine engines also include a plurality of rotating and stationary components. These components may be secured and positioned axially via stack nuts and spacers so as to take in tolerances to minimize the overall size and weight of the gas turbine engine. A stack nut fits on an outer diameter of and is inhibited from rotation against an adjacent rotatable component by using a key washer. The key washer fits in a set of slots in the stack nut and the adjacent rotatable component. The key washer itself has a series of tabs, or keys, that are sized, numbered, and oriented such that the key washer interfaces and is retained between the stack nut and the adjacent rotatable component. Unfortunately, the key washer is an extra engine part, providing extra complexity and cost to the gas turbine engine. Moreover, where space is limited in the gas turbine engine, insertion of the key washer between the stack nut and adjacent rotatable component may be difficult.